A driving assistance device has been known for predicting a risk of contact between a host vehicle and an obstacle around the host vehicle in a case where the host vehicle is traveling under driving behavior according to at least one or more normative behavior candidates, the normative behavior candidates being candidates for normative driving behavior of the host vehicle for a situation around the host vehicle (see Japanese Patent Application Publication No. 2011-096105).
Assuming that there is an obstacle moving toward the host vehicle with constant acceleration in a blind spot for the host vehicle, Japanese Patent Application Publication No. 2011-096105 calculates a potential contact risk and determines the driving behavior based on the contact risk.
In Japanese Patent Application Publication No. 2011-096105, however, proportion of the blind spot for the host vehicle with respect to a region on a map, which affects the contact risk, is not taken into account. Thus, driving behavior excessively focusing on safety may be determined, and this may make surrounding people uncomfortable.